Paper laminated metal sheet

ABSTRACT

The present invention provides a paper-laminated metal sheet having a structure in which at least one sheet of paper is laminated on at least one side of a metal plate via a pressure sensitive adhesive agent or an adhesive agent layer, and a protective layer is formed on a top surface of the paper-laminated side. With this structure, the paper-laminated metal sheet can be processed without wetting the paper with water, while thereby preventing the paper from being torn. In addition, the aesthetic appearance derived from the paper is kept for a long period of time. Due to high strength and processability derived from the metal base material, and high aesthetic appearance unbelievable for a metal plate derived from the paper, the paper-laminated metal sheet is valuable in various applications as a novel material.

TECHNICAL FIELD

The present invention relates to a paper-laminated metal sheet includinga metal base material and paper laminated on the metal base material.Specifically, the present invention relates to a paper-laminated metalsheet with high aesthetic appearance which has various applicationsincluding construction materials for houses and buildings such as innerwall materials, floor materials, ceiling materials, interior materials,panels, and doors, casing members for furniture such as lockers,cabinets, and counters, casing members for electric appliances, interiormaterials for vehicles such as cars, trains, and ships, and vessels andmetal fixtures.

BACKGROUND ART

In an attempt to provide metal sheet on which aesthetic appearance canbe made, various techniques have been developed, and the followingmethods have been in the actual use. In one method, a resin coating isapplied to the surface of a plated or non-plated metal base material.After that, beautiful colors, designs or patterns may be printedthereon. As a result, a beautifully coated metal sheet is obtained. Inanother method, a metal base material is subjected to hot rolling, and ablack oxide layer naturally formed during the hot rolling is utilized tomake designs thereon. There is also a method for providing a steel sheetor a titanium alloy sheet formed with decorative coatings in variouscolors. In this method, an oxide layer of navy blue or other colors isartificially formed onto the surface of the metal base material. Themetal sheets obtained in these conventional methods have beautiful andaesthetic appearance formed; however, a coolness and touch feelinheriting from metal sheets remain.

On the other hand, film-laminated metal sheets are also known. Thefilm-laminated metal sheets are formed by laminating a film of polyvinylchloride, polyolefin, or an acrylic resin onto a metal base material.The laminated films are effective in giving high corrosion resistanceand scratching resistance to the metal sheets; however, few of them haveaesthetic appearance property. In addition, these laminated films arethermoplastic in applications where the processability is important, andtherefore, they have low heat resistance. As laminated films, vinylpolyvinyl chloride films have been widely used; however, they generateharmful gas when burned, causing an air-pollution problem.

In order to solve the above-described problems of the prior arts,studies have been proceeded to develop a new type of laminated metalsheets. For example, Japanese Unexamined Patent Publication No. 7-256822discloses a paper-laminated metal sheet including a metal base materialand paper laminated on the metal base material via an adhesive agent.The features of this invention seem to reside in that, when thepaper-laminated metal sheet is subjected to a bending process, theportion to be bent is wet -with water and then is bent, therebypreventing the paper from being torn. However, the step of wetting theportion to be bent of the paper-laminated metal sheets one by one makesthe production process complicated, and lowers the productivity. Inaddition, whereas the wet paper-laminated metal sheet can easily bent,the strength of its paper is lowered. As a result, a problem arises inthat the paper is damaged or torn during the processing. There is also aproblem that, in the state of being wet with water, the paper loses itsadhesiveness to the metal base material. Depending on the processings,the paper may peel off from the metal base material.

The present invention has been achieved in view of the above-describedsituation, and an objective thereof is to provide a paper-laminatedmetal sheet which can be processed without wetting with water, whilepreventing the paper from being torn with, and which keeps the aestheticappearance derived from the paper for a long period of time.

Another objective of the present invention is to provide apaper-laminated metal sheet with high strength and processabilityderived from the metal base material, as well as unbelievably highaesthetic appearance for a metal plate derived from paper, whereby thepaper-laminated metal sheet is valuable as a novel material havingvarious applications.

DISCLOSURE OF INVENTION

According to the present invention, a paper-laminated metal sheet has astructure in which at least a sheet of paper is laminated on at leastone side of a metal base material via a pressure sensitive adhesiveagent or an adhesive agent layer, and a protective layer is formed onthe top surface of the paper-laminated side. With this structure, thepaper-laminated metal sheet has a soft and warm touch derived from thepaper while eliminating an inorganic appearance and a cold touchinherent to metals. In addition, the protective layer prevents the paperfrom being damaged during the time when the paper-laminated metal sheetis processed or is used for products. In addition, when the pre-printedpaper is used, higher aesthetic appearance is attained. For example,when paper printed with a woodgrain pattern is used, the metal plate isvaluable in various applications as a novel material with high qualityappearance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) is a cross-sectional view of a paper-laminated metal sheetaccording an example of the present invention. FIG. 1(b) is across-sectional view of a paper-laminated metal sheet shown in FIG. 1(a)from which the protective layer is omitted.

FIG. 2 is a cross-sectional view showing a paper-laminated metal sheetaccording to another example of the present invention.

FIG. 3 is a plane-view of decorative paper on which a woodgrain patternwith a three-dimensional effect is printed.

FIG. 4 is a cross-sectional view taken along the line A—A of FIG. 3.

BEST MODE FOR CARRYING OUT THE INVENTION

A paper-laminated metal sheet of the present invention has a structurein which at least a sheet of paper is laminated on at least one side ofa metal base material via a pressure sensitive adhesive agent or anadhesive agent layer, and a protective layer is formed on the topsurface of the paper-laminated side.

The protective layer preferably is a water-repellent resin film, andspecifically, a water-repellent resin film having a water contact angleof 60 degree or more measured by a liquid drop method at 23° C. Theprotective layer with water repellency prevents the paper from beingtorn, and also avoids water penetration through the paper to protect themetal base material from corrosion by water.

In the paper-laminated metal sheet of the present invention, the peelstrength at 180 degree between the metal base material and the paperlaminated on the metal base material preferably is in the range between0.01 to 5.0 kgf/10 mm in width, and the peel strength preferably issmaller than the breaking strength of the paper itself. In addition, itis preferable to use paper having a maximum elongation of 2% or more.The paper-laminated metal sheet, which satisfies these preferablerequirements has high processability. Therefore, the paper-laminatedmetal sheet eliminates the step of wetting paper which makes theprocessing complicated and makes the protection of the paper from damagedifficult.

The paper preferably is decorative paper having depressions and/orprotrusions on its surface, and the depressions and/or the protrusionshave colors different from the surrounding portions to form a visuallyrecognizable design. Especially preferable is decorative paper having astructure in which at least a printing ink layer and a resin layer isformed on a paper base material, and the depressions and/or theprotrusions are formed on the surface of the resin layer. Through theuse of the decorative paper with this structure, various designs can bemade by the printing ink layer, and the depressions and/or theprotrusions of the resin layer create a three-dimensional effect on thedesign.

When decorative paper printed with a woodgrain pattern is used, thepaper-laminated metal sheet is valuable in various applications as anovel material with high quality appearance. More preferably, the resinlayer of the decorative paper has depressions to be dark-coloredportions of the woodgrain pattern. In this case, the woodgrain patternof the decorative paper resembles to a natural wood in appearance. Fromthis point of view, the decorative paper preferably has the followstructure. On the entire surface of a base paper material, a firstprinting ink layer to be light-colored portions of the woodgrain patternis formed directly or via another layer. Next, a second printing inklayer to be dark-colored portions of the woodgrain pattern is formed,and then, a resin layer containing a curing agent is formed on the firstand second printing ink layers. The second printing ink layer is formedusing ink including a compound which reacts with the curing agent of theresin layer to generate gas. The gas creates bubbles in the resin layerat least the portions positioned on the second printing ink layer, andthe bubbles foam and bulge the resin layer. The whole of the foamedportions of the resin layer are ground and removed (i.e. hollowed out)to form depressions of which bottoms coincide with the top surface ofthe second printing in layer. Instead of the compound which generatesgas through the reaction with the curing agent of the resin layer, acompound which decomposes and generates gas through the application ofheat may be used to foam and bulge the resin layer.

The paper-laminated metal sheet of the present invention are typicallyused for construction materials, casing members for furniture andelectric appliances, and interior materials for vehicles and ships. Itshould be noted, however, that the paper-laminated metal sheet is notlimited to these applications, but may be used in other applications.

Hereinafter, the present invention will be further described in detail.As described above, the paper-laminated metal sheet of the presentinvention has a structure in which paper is laminated on at least oneside of the metal base material, and a protective layer is formed on thetop surface of the paper-laminated side. The paper-laminated metal sheethas a warm touch derived from the paper which is a natural material, andalso has high processability and strength derived from the metal basematerial.

The metal base material is in the form of plate (sheet) made of metal,and is not limited to a specific kind. The examples thereof includesteel sheets, copper sheets, aluminum sheets, titanium sheets, andvarious alloy sheets. Before the paper is laminated, the metal basematerial may be subjected to known surface treatments for givingcorrosion resistance. The thickness of the metal base material isproperly determined in accordance with the intended use of thepaper-laminated metal sheet. Metal foil also may be used as the metalbase material.

The paper used in the present invention is paper produced byintertwining and agglutinating plant fibers or other fibers into theform of sheet. The thickness and the basis weight of the paper isproperly determined in accordance with the intended use of thepaper-laminated metal sheet. In general, the paper preferably has thebasis weight of 15 to 200 g/m². Also employable is paper which isprinted with any patterns or is subjected to physical processings suchas embossing, crepe processing, corrugating processing, and calenderingprocessing in its production. Also preferable is printed paper such asdecorative paper used for decorating wooden construction materials andwooden furniture. In addition, various kinds of decorative paper such aswoodgrain paper, imitation leather, and papers printed through knownprinting processes also may be used. When paper formed with a protectivelayer on its entire surface beforehand is used as the paper of thepresent invention, there is no need of newly forming another protectivelayer. In this case, by just laminating the paper formed with theprotective layer on the metal base material, the paper-laminated metalsheet of the present invention can be obtained. When the specialdecorative paper which will described later is used, higher aestheticappearance is attained.

The paper preferably has a maximum elongation of 2% or more, in order togive high processability to the paper-laminated metal sheet. If thepaper has the maximum elongation of less than 2%, the paper is easilytorn during the processing. The paper preferably has the breakingstrength larger than the peel strength at 180 degree (which will bedescribed later) between the paper and the metal base material. Thebreaking strength (kgf/10 mm in width) and the maximum elongation (%)are measured in the state where the sample piece is pulled at a speed ofImm/min at an atmosphere temperature of 23° C. and a humidity of 80%.

The paper-laminated metal sheet has a structure in which the paper islaminated on at least one side of the metal base material, and on thetop surface of the paper-laminated side (one or both sides of the metalbase material), a protective layer is formed. The protective layer isformed on the paper directly or via another layer before or after thepaper is laminated on the metal base material. “Another layer” is notspecifically limited. In order to perfectly protect the paper, thethickness of the protective layer preferably is 5 μm or more, but is notrequired to be excessive. In general, the thickness is 10 to 30 μm.

The protective layer preferably has water-repellency. Especiallypreferable as the protective layer is a water-repellent resin film whichhas a water contact angle of 60 degree or more measured by a liquid dropmethod at 23° C. The protective layer with water repellency prevents thepaper from being torn and contaminated by water-based liquid, and avoidswater penetration through the paper to protect the metal base materialfrom corrosion by water.

The contact angle was measured by a liquid drop method in which waterdroplets were formed on the sample piece of the protective layer, andthe contact angle of the droplets were measured at an atmospheretemperature of 23° C., using a CD-DT . A-type contact angle metermanufactured by Kyowa Kaimen Kagaku Co., Ltd.

Examples of the material for forming the protective layer includepolyorefin resins, silicone resins, fluorine resins, polyurethaneresins, epoxy resins, alkyd resins, acrylic resins, polyester resins,and vinyl acetate resins. Resins containing chlorine atoms such aspolyvinyl chloride and polyvinylidene chloride are not suitable in thepresent invention, because these resins generate harmful gas whenburned. In the present invention, the “resin” may include water, organicsolvent, and other known additives such as curing agents, curingcatalysts, viscosity thickners, wet property modifiers, plasticizers,and fillers in accordance with necessity.

The method for forming the protective layer is not specifically limited,and the following methods may be employed, for example. In one method,the resin for forming the protective layer is applied on the paperdirectly or via another layer by a method such as roll coating, spraycoating, nozzle coating, dip coating, and bar coating. The applied resinis heated and dried to form the protective layer. The resin may be anyof aqueous type (i.e. emulsion type), solvent type, and non-solventtype. In another method, the film made of the resin is laminated on thepaper using an adhesive agent (which will be described later) ifnecessary, by a method such as dry laminating, wet laminating, and hotmelt laminating. There is also a method in which the resin in the moltenstate is directly extruded through a die onto the paper and the like.

The paper is laminated on the metal base material via a pressuresensitive adhesive agent or an adhesive agent (hereinafter, simplyreferred to as an adhesive agent for the sake of convenience). Theadhesive agent is directly applied onto the metal base material, or afilm made of the adhesive agent is laminated on the metal base material.The method for applying the adhesive agent is not specifically limited,and the same methods as used for forming the protective layer may beemployed. Examples of the adhesive agent include: vinyl acetate resinssuch as polyvinyl acetate and an ethylene-vinyl acetate copolymer (EVA);acrylic resins such as a poly(meth)acrylate and/or esters thereof or acopolymer of (meth)acrylate and/or esters thereof and other monomerssuch as styrene and vinyl acetate; polyurethane resins; polyesterresins; polyorefin resins; polystyrene resins such as SBS and SIBS;rubbers such as natural rubber and synthetic rubber; and other knowadhesive agents. The adhesive agent may be any of emulsion type, solventtype, and non-solvent type.

The amount of the adhesive agent is 0.5 to 40 g/m² as the weight perarea after being dried. If the amount is less than 0.5 g/m², theadhesion between the paper and the metal base material becomes weak.Contrary to this, if the amount is larger than 40 g/m², wrinkles arecreated on the paper, and the adhesion effect is saturated. Morepreferable lower limit of the amount of the adhesive agent is 3.0 g/m²,and more preferable upper limit thereof is 15 g/m².

After the adhesive agent is applied, the paper is laminated thereon.When the adhesive agent includes a solvent, the paper is preferablylaminated on the adhesive agent layer before the solvent is completelydried. When the adhesive agent has a fluidity through the application ofheat or is a thermosetting adhesive agent, the paper is preferablylaminated on the adhesive agent layer before the adhesive agent issolidified and loses its fluidity. The adhesive agent with fluiditypenetrates into the paper through its minute openings, and increases theadhesiveness of the paper. However, in the case where the paper has thinthickness and small basis weight, the adhesion agent may too deeppenetrate into the paper, and exudes to the surface of the paper (i.e.to the surface on the side opposite to the metal base material). Inorder to avoid this trouble, the timing of laminating the paper isproperly determined taking into consideration the drying and solidifyingspeed of the adhesive agent. After the paper is laminated, it ispreferable that the paper-laminated metal sheet is passed through a hotair drying equipment to completely drying and curing the adhesive agent.The same cares as those described above are preferably taken in theformation of the protective layer.

The peel strength at 180 degree between the paper and the metal basematerial attached to each other via the adhesive agent layer ispreferably in the range between 0.01 to 5.0 kgf/10 mm in width, and thepeel strength is smaller than the breaking strength of the paper itself.The paper-laminated metal sheet of the present invention, whichsatisfies these requirements, can be processed without wetting the paperwith water while preventing the paper from being torn. It is recommendedthat the kinds of the adhesive agent and the paper are properly selectedso that these requirements are satisfied.

If the peel strength at 180 degree is smaller than 0.01 kgf/10 mm inwidth, the adhesion of the paper to the metal base material becomesweak. The paper may peel off with time. The peel strength at 180 degreeof larger than 5.0 kgf/10 mm is not preferable as well, because theadhesion of the paper to the metal base material becomes too strong. Inthis case, the paper cannot resist being deformed in the processing, andmay be torn. More preferable peel strength at 180 degree is in the rangebetween 0.1 to 0.5 kgf/10 mm. The peel strength at 180 degree ismeasured by “the peeling test at 180 degree” in conformance withJapanese Industrial Standards (JIS) Z 0 237 at a peeling speed of 200mm/min at an atmosphere temperature of 23° C. and a humidity of 80%.

The number of paper is not limited to one, but two or more sheets ofpaper may be used. When two or more sheets of paper are used, theadhesive agent is applied on the first paper, and then the second paperis laminated thereon. The second paper (i.e. the paper laminated on thefirst paper and positioned on the opposite side of the metal basematerial) may be partially cut. In this case, the lower paper is seenthrough the cut portion of the upper paper.

By laminating a plurality of partially-cut papers having differentcolors from each other, the paper-laminated metal sheet exhibitsbeautiful appearance. The protective layer is formed on the top paper.

In order to give higher aesthetic appearance to the paper-laminatedmetal sheet, special decorative paper may be used. For example, thedecorative paper may be formed with depressions and/or protrusions onits surface, and the depressions and/or the protrusions have differentcolors from the surrounding portions to form a visually recognizabledesign. The depressions and/or the protrusions are preferably arrangedto coincide with the pattern to be printed. Thus-formed design has athree-dimensional effect, and gives high aesthetic appearance to thedecorative paper.

FIG. 1(a) is a cross-sectional view showing a paper-laminated metalsheet including a decorative paper formed with depressions andprotrusions to create a three-dimensional effect. FIGS. 1(b) is across-sectional view of the paper-laminated metal sheet of FIG. 1(a)from which the protective layer is omitted. On one side of a metal basematerial 1, decorative paper 3 is laminated via an adhesive agent layer2, and a protective layer 5 is further formed on the decorative paper 3.Depressions 4 formed on the decorative paper 3 are left as depressions 4a after the formation of the protective layer 5 formed on the decorativepaper 3. FIG. 2 is a cross-sectional view showing a paper-laminatedmetal sheet according to another example where depressions 4 arecompletely filled with a protective layer 5. In the present invention,any of these structures are employable; however, preferable is thestructure shown in FIG. 1(a) where the depressions are left as thedepressions 4 a, in order to keep high aesthetic appearance derived fromthe decorative paper. Therefore, it is preferable that the depressionsof the decorative paper is not completely filled with the protectivelayer. To this end, it is recommended that proper arrangements are madein the formation of the protective layer, for example, the protectivelayer is made into thin thickness.

The recommended method for producing the decorative paper having thedepressions and protrusions which correspond to the pattern to be madesuch as those described above is as follows. First, a printing ink layeris formed on a paper base material which is the decorative paper, andthen, a resin layer is formed thereon. After that, the depressions andprotrusions are formed in the resin layer.

In order to form the depressions and protrusions corresponding to theprinting pattern to be made in the resin layer, the following methodsmay be employed:

(1) On the paper base material, the printing ink layer is partiallyformed, and a resin (i.e. coating) layer is formed thereon. The ink usedfor forming the printing layer contains a compound which reacts with thecuring agent contained in the resin layer and generates gas. The gasturns bubbles in the resin layer, and the parts of the resin layer whichpositioned on the printing ink layer, is foamed and bulged by thebubbles, consequently protrusions are formed (Japanese Unexamined PatentPublication No. 47-329 11).

(2) In the same manner as the above method (1), the printing ink layergenerates gas which turns bubbles in the resin layer. The gas turnsbubbles in the resin layer, and the parts of the resin layer whichpositioned on the printing ink layer, is foamed and bulged by thebubbles, consequently protrusions are formed (Japanese Unexamined PatentPublication No. 47-32911). Then, the whole of the protrusions are groundto form depressions in such a manner that the top surface of the secondprinting ink layer is exposed to outside to be the bottoms of thedepressions (Japanese Unexamined Patent Publications Nos. 48-674 and48-777).

(3) In the same manner as the above method (2), the depressions areformed in the resin layer, except that the ink layer is made of the inkcontaining “a compound which is decomposed through the application ofheat to generate gas”, instead of “the compound which reacts with thecuring agent of the resin layer to generate gas” (Japanese UnexaminedPatent Publication NO. 63-77571).

Hereinafter, the terms “the three-dimensional patterns” and “depressionsand protrusions corresponding to printed patterns” will be described,taking decorative paper having “a woodgrain pattern” as an example. FIG.3 is a diagram showing an example of the woodgrain pattern. Thewoodgrain pattern has annual rings of wood, and specifically, isobserved in a flat wooden board. In the decorative paper shown in FIG.3, the actual color of the black-colored portion is dark brown, and theactual color of the white-colored portion is light brown. In the presentinvention, the terms “the three-dimensional patterns” and “depressionsand protrusions corresponding to the printed patterns” mean that thedepressions form the black-colored portion of the woodgrain pattern whenthe cross-section of the decorative paper is viewed (or alternatively,the protrusions may form the black-colored portion, as far as thedepressions and the protrusions correspond to the pattern).

FIG. 4 is a cross-sectional view taken along the line A—A of FIG. 3. Ona paper base material 31, an ink layer 32, 32 to be a dark-coloredportion of the woodgrain pattern is partially formed. On the remainingportion of the paper base material 31 where no ink layer is formed, aresin layer 33 is formed. The ink layer 32 has a height lower than theresin layer 33 to create depressions 4. On the ink layer 32 and theresin layer 33, a protective layer 5 is formed in such a manner that theprotective layer 5 does not completely filling the depressions 4 toleave depressions 4 a. The paper base material originally has a colorlighter than the ink layer 31, and forms the light-colored portion ofthe woodgrain pattern. The combination of the ink layer 32 and the paperbase material creates the woodgrain pattern shown in FIG. 3 on thedecorative paper. It is preferable that the depth of the depressions 4 aafter the formation of the protective layer 5 is 12 to 14 μm, becausethus-formed decorative paper has a touch close to a natural wood.

In order to prepare the decorative paper having a woodgrain pattern suchas shown in FIGS. 3 and 4, the methods disclosed in above-mentionedJapanese Unexamined Patent Publications Nos. 48-674, 48-777, and63-77571 may be employed. In order to foam and bulge the resin layer,the ink layer is formed using the ink containing a compound which reactswith the curing agent contained in the resin layer to generate gas, oralternatively, the ink layer is formed using the ink containing acompound which is decomposed through the application of heat to generategas. In accordance with the desired color and pattern of the design,various modifications may be made. For example, a first printing inklayer to be the light-colored portion of the woodgrain pattern isformed, and after that, a second printing ink layer to be thedark-colored portion of the woodgrain pattern is formed (and viceversa). Alternatively, prior to forming the first printing ink layer, alayer printed into a solid color may be formed on the entire surface ofthe paper base material.

The decorative paper having a three-dimensional pattern is not limitedto that shown in FIGS. 3 and 4, but there are also other types ofdecorative paper employable as “the decorative paper having thedepressions and the protrusions corresponding to the pattern”. Forexample, decorative paper is formed with the depressions and theprotrusions, but only either of the depressions or the protrusions arecolored. Alternatively, decorative paper itself is provided with apattern using a colorant and the like, and then, the depressions andprotrusions corresponding to the pattern are formed.

The paper-laminated metal sheet of the present invention has variousapplications. Hereinafter, typical applications thereof and the effectobtained through the use thereof will be described.

(A) Use for construction materials

In this application, the paper-laminated metal sheet can be used asconstruction materials for houses and buildings. Specifically, thepaper-laminated metal sheet can be used as inner wall materials, ceilingmaterial, flooring material, interior material, partitioning units,panels, doors, sash, and the like. There are also such applications asmetallic parts including hinges and locks. Through the use of thepaper-laminated metal sheet for applications where metal plates havebeen used alone, the following advantages can be obtained:

(1) Whereas metal plates alone have a coolness and a cold touch, thepaper-laminated metal sheet has a warmth and a soft touch. At the sametime, it has a calm and peaceful appearance;

(2) Due to the excellent aesthetic appearance, the paper-laminated metalsheet is useful as a novel material with high quality appearanceunbelievable for a metal sheet;

(3) The paper-laminated metal sheet has high processability and strengthderived from the metal base material, and also has high corrosionresistance which is given by the paper and the protective layer;

(4) The paper-laminated metal sheet has higher fireproof property andresistance to spread of fire than paper alone when burned. Even ifcigarette fire is pressed to the paper-laminated metal sheet, the metalbase material adsorbs the heat of cigarette, and therefore, fire is hardto spread. Even if the paper-laminated metal sheet burns, no harmful gasis generated, unlike the case where polyvinyl chloride steel sheet isburned;

(5) The paper-laminated metal sheet has remarkably higher strength thanpaper alone; and

(6) The protective layer prevents the paper from being torn andcontaminated. Therefore, the aesthetic appearance derived from the paperis semipermanently kept.

When the paper-laminated metal sheet is used for decorative laminatessuch as woody decorative laminates, further advantages are obtained inaddition to those described in points (1) to (4), such as highprocessability and resistance to termite, as well as being recyclable.In addition, when the paper-laminated metal sheet is used for metallicparts, they can be made into the same designs and feelings as those ofthe main body to which the metallic parts are mounted.

A matching is created between the main body and the metallic parts,causing no mismatching and strangeness therebetween, thereby realizing adesign of higher sense.

(B) Use for furniture materials

The paper-laminated metal sheet can be used for all the furniture whichhas been conventionally made of steel, such as desks, chairs, lockers,cabinets, counters, stands, bookshelves, partitions, and beds. Inaddition, it is also applicable to furniture which has beenconventionally made of woods or resins only. When the paper-laminatedmetal sheet is used for furniture, the same advantages as thosedescribed in the above points (1) to (6) for use in constructionmaterials can be obtained. Furthermore, when the paper-laminated metalsheet is used for metallic parts of furniture, the matching is createdbetween the furniture and the metallic parts with no mismatching andstrangeness, thereby realizing a design of higher sense.

(C) Use for casing members of electric appliances

The paper-laminated metal sheet is usable for casing members of electricappliances such as televisions, refrigerators, washing machines, airconditioner, and lightening equipment. Specifically, the paper-laminatedmetal sheet is usable for casing members of electric applicances whichhave been conventionally made of metal sheet alone, thereby realizing adesign of high sense. When the paper-laminated metal sheet is used forelectric appliances, the same advantages as those described in thepoints (1) to (6) for use in construction materials can be obtained. Inaddition, it is also applicable as constituent elements for otherelectric appliances.

The applications of the paper-laminated metal sheet of the presentinvention is not limited to those described in the above points (A) to(C), but there are also other various applications including, forexample, interior materials for vehicles such as cars, trains, andships, metal parts, and vessels.

EXAMPLES

Hereinafter, the present invention will be further described in detailwith reference to examples. However, it is to be noted that variouschanges and modifications will be apparent to those skilled in the art.Therefore, unless otherwise such change and modifications depart fromthe scope of the invention, they should be construed as being includedtherein.

EXAMPLES AND COMPARATIVE EXAMPLES

The metal base materials shown in Tables 1 to 5 were subjected tochromate treatment (Cr:30 mg/m²), and then, an acryl-based pressuresensitive adhesive agent was applied thereon by a roll coating method insuch a manner that the weight after being dried was 10 g/m². After that,the papers (i.e. decorative paper, paper, embossed paper, crape paper,corrugated paper, calendered paper, and colored polyvinyl chloride film)were respectively laminated on the metal base materials via the adhesiveagent layer, and were dried at 80° C. (metal sheet temperature) for 1minute. Then, the resins shown in Tables 1 to 5 were respectivelyapplied on the paper, and were dried to form protective layers. InTables 1 to 5, the thickness (μm) means the thickness of the protectivelayer after being dried. As a result, paper-laminated metal sheets wereobtained. The characteristics of the paper-laminated metal sheets wereevaluated by the following methods. The evaluation results are shown inTables 1 to 5.

All the metal base materials had a thickness of 0.3 mm except for thealuminum foil used in Example No. 36. The aluminum foil used in ExampleNo. 36 had a thickness of 15 μm. The decorative paper had a basis weightof 50 g/m² and was formed with a three-dimensional woodgrain pattern. InComparative Examples 44 to 47, the paper had a breaking strength largerthan the peel strength between the paper and the metal base material. InComparative Examples 48 to 49, the peel strength of the paper and themetal base material was smaller than the preferable value defined in thepresent invention. In Comparative Examples 57 to 60, the maximumelongation of the paper did not fall within the preferable range definedin the present invention. In Comparative Example 56, a plywood veneerboard was used instead of a metal base material.

Method for evaluating the characteristics

Contact Angle with Water

The contact angle with water was obtained by a liquid drop method inwhich water droplets were made on the protective layer, and the contactangle with the water droplets was measured at an atmosphere temperatureof 23° C. using a CD-DT . A-type contact angle meter manufactured byKyowa Kaimen Kagaku Co., Ltd.

Peel Strength at 180 Degree

The peel strength at 180 degree (kgf/10 mm in width) was measured inconformance with Japanese Industrial Standards (JIS) Z 0 237.Specifically, the metal base material and the paper (10 mm in width)laminated on the metal base material were pinched with the upper andlower chucks respectively. The resistance force obtained by peeling offat a speed of 200 mm/min was measured. The measurement was conducted atan atmosphere temperature of 23° C. and humidity of 80%.

Breaking Strength and Elongation of Paper

The breaking strength (kgf/10 mm in width) and the maximum elongation(%) of the paper itself were the values obtained when the sample piecepaper was tensed at a speed of 1 mm/min. The measurement was conductedat an atmosphere temperature of 23° C. and humidity of 80%.

Processability-1

The bending test at 90 degree was conducted at R:1 mm. The breaking(i.e. cracking) state and the peeling state of the paper at the bentportion were visually observed, and were evaluated under the followingstandards.

⊚: No cracks were observed.

◯: Small number of cracks were observed.

Δ: A large number of cracks were observed.

×: Bending test could not be conducted.

Processability-2

The bending test at 180 degree was conducted. The breaking state and thepeeling state of the paper at the bent portion were visually observed,and were evaluated under the same standards as used in the evaluation ofthe processability-1.

Adhesiveness

The peel strength at 180 degree (kgf/10 mm in width) between the paperand the metal base material was measured, and was evaluated under thefollowing standards.

⊚: The peel strength at 180 degree was 0.01 or more.

◯: The peel strength at 180 degree was larger than 0.008 to smaller than0.01.

Δ: The peel strength at 180 degree was larger than 0.005 to 0.008.

×: The peel strength at 180 degree was 0.005 or smaller.

Aesthetic Appearance

Whether or not the respective paper-laminated metal sheets had theaesthetic appearance under the following standards.

⊚: Paper having high aesthetic appearance was laminated on the metalbase material.

Δ: A colored polyvinyl chloride film was laminated on the metal basematerial.

×: Nothing was laminated on the metal base material.

Safety

The materials other than the metal base material (i.e. an adhesiveagent, paper, a colored polyvinyl chloride film, and a protective layer)were put into a tube furnace, and were heated at about 700° C. to beburn. The generated gas was trapped in a cold trap tube, and then wasput into a tedler bag. The gas was analyzed by a gas chromatography, andwas evaluated under the following standard.

◯: No harmful gas (chlorine-containing gas) was generated (at the levelof 30 μg per 1 g of sample piece).

×: Harmful gas was generated (at the level of 3000000 μg per 1 g ofsample piece).

Chemical Resistance

Onto the protective layer, 5% acetic acid aqueous solution and 1% sodiumhydroxide aqueous solution were respectively dropped. Then, theprotective layer was covered with a watch glass. After 24 hours, the 5%acetic acid aqueous solution and 1% sodium hydroxide aqueous solutionwere wiped out. The state of the surface of the protective layer wasvisually observed, and was evaluated under the following standards.

⊚: There was no change in the color of the surface.

◯: The color of the surface was slightly changed or degraded.

Δ: The color of the surface was remarkably changed or degraded.

×: The color of the surface was seriously changed or degraded.

Contamination Resistance

Onto the protective layer, oily marking ink of an oil magic marker andsoy source were respectively dropped. Then, the protective layer wascovered with a watch glass. After 24 hours, the ink and the soy sourcewere wiped out. The state of the surface of the protective layer wasvisually observed, and was evaluated under the following standards.

⊚: No contamination was observed.

◯: A slight contamination was observed.

Δ: A remarkable contamination was observed.

×: A serious contamination was observed.

Resistance to Spread of Fire

The resistance of spread of fire was measured by a self-extinguishingcharacteristics test in conformance with Japanese Industrial Standards K6744, and was evaluated under the following standards.

⊚: Fire extinguished immediately.

◯: Fire extinguished within 5 seconds.

Δ: Fire extinguished within 10 seconds.

×: Fire extinguished in 10 seconds or longer.

The meanings of the abbreviations in Tables 1 to 5 are as follows.

PU: polyurethane resin

EPO: epoxy resin

UPE: polyester resin

AL: alkyd resin

SB: styrene-butadiene copolymer

VA: vinyl acetate resin

PVC: polyvinyl chloride

The unit of the peel strength at 180 degree and the breaking strength ofthe paper is kgf/10 mm in width.

TABLE 1-1 Kind & thick- ness of Contact Break- Elonga- Con- Resis-protec- angle Peel ing tion Pro- Pro- Aes- Chemi- tamin- tance Metaltive with strength strength of cessa- cessa- Adhe- thetic cal ation tobase layer water at 180 of paper bility- bility- sive- appear- Safe-resis- resis- spread material Paper (μm) (°) degree* paper* (%) 1 2 nessance ty tance tance of fire EXAM- PLE 1 Fused Dec- PU:20 105 1.5 5.0 4.5⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- ora- plated tive steel paper sheet 2 Fused Dec-PU:20 105 2.0 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- ora- plated tive steel papersheet 3 Fused Dec- PU:20 105 3.0 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- ora- platedtive steel paper sheet 4 Fused Dec- PU:20 105 1.0 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚⊚ Zn- ora- plated tive steel paper sheet 5 Fused Dec- PU:20 105 0.5 5.04.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- ora- plated tive steel paper sheet 6 Fused Dec-PU:20 105 0.1 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- ora- plated tive steel papersheet 7 Fused Dec- PU:20 105 0.05 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- ora-plated tive steel paper sheet

TABLE 1-2 Kind & thick- ness of Contact Break- Elonga- Con- Resis-protec- angle Peel ing tion Pro- Pro- Aes- Chemi- tamin- tance metaltive with strength strength of cessa- cessa- Adhe- thetic cal ation tobase layer water at 180 of paper bility- bility- sive- appear- Safe-resis- resis- spread material Paper (μm) (°) degree* paper* (%) 1 2 nessance ty tance tance of fire EXAM- PLE  8 Fused Decora- PU:20 105 0.015.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated paper steel sheet  9 FusedDecora- PU:20 105 1.5 4.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated papersteel sheet 10 Fused Decora- PU:20 105 1.5 3.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn-tive plated paper steel sheet 11 Fused Decora- PU:20 105 1.5 2.0 4.5 ⊚ ⊚⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated paper steel sheet 12 Fused Decora- PU:20 1051.5 5.0 4.0 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated paper steel sheet 13 FusedDecora- PU:20 105 1.5 5.0 3.0 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated papersteel sheet 14 Fused Decora- PU:20 105 1.5 5.0 2.0 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn-tive plated paper steel sheet

TABLE 2-1 Kind & thick- ness of Contact Break- Elonga- Con- Resis-protec- angle Peel ing tion Pro- Pro- Aes- Chemi- tamin- tance Metaltive with strength strength of cessa- cessa- Adhe- thetic cal ation tobase layer water at 180 of paper bility- bility- sive- appear- Safe-resis- resis- spread material Paper (μm) (°) degree* paper* (%) 1 2 nessance ty tance tance of fire EXAM- PLE 15 Fused Decora- PU:20 105 1.5 5.06.0 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated paper steel sheet 16 Fused Decora-PU:5  90 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated paper steel sheet17 Fused Decora- PU:10 100 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive platedpaper steel sheet 18 Fused Decora- PU:15 103 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚Zn- tive plated paper steel sheet 19 Fused Decora- PU:30 110 1.5 5.0 4.5⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated paper steel sheet 20 Fused Decora- PU:40113 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated paper steel sheet 21Fused Decora- AR:20 103 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive platedpaper steel sheet

TABLE 2-2 Kind & thick- ness of Contact Break- Elonga- Con- Resis-protec- angle Peel ing tion Pro- Pro- Aes- Chemi- tamin- tance Metaltive with strength strength of cessa- cessa- Adhe- thetic cal ation tobase layer water at 180 of paper bility- bility- sive- appear- Safe-resis- resis- spread material Paper (μm) (°) degree* paper* (%) 1 2 nessance ty tance tance of fire EXAM- PLE 22 Fused Decora- EPO:20 100 1.55.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated paper steel sheet 23 FusedDecora- UPE:20 102 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated papersteel sheet 24 Fused Decora- AL:20  80 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn-tive plated paper steel sheet 25 Fused Decora- SB:20  60 1.5 5.0 4.5 ⊚ ⊚⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated paper steel sheet 26 Fused Decora- VA:20 1001.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated paper steal sheet 27Electric Decora- PU:20 105 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive platedpaper steel sheet 28 Electric Decora- PU:20 105 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚⊚ ⊚ Zn—Ni tive plated paper steel sheet

TABLE 3-1 Kind & thick- ness of Contact Break- Elonga- Con- Resis-protec- angle Peel ing tion Pro- Pro- Aes- Chemi- tamin- tance Metaltive with strength strength of cessa- cessa- Adhe- thetic cal ation tobase layer water at 180 of paper bility- bility- sive- appear- Safe-resis- resis- spread material Paper (μm) (°) degree* paper* (%) 1 2 nessance ty tance tance of fire EXAM- PLE 29 Alloyed Dec- PU:20 105 1.5 5.04.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ fused ora- Zn- tive plated paper steel sheet Dec- 30Fused Al- ora- PU:20 100 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ plated tive steelpaper sheet 31 Fused Dec- PU:20 105 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn—Alora- (55) tive plated paper steel sheet 32 Fused Dec- PU:20 105 1.5 5.04.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn—Al ora- (5) tive plated paper steel sheet 33 ColdDec- PU:20 105 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ stretched ora- steel tiveplate paper 34 Heat Dec- PU:20 105 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ stretchedora- sheet tive steel paper 35 Al sheet Dec- PU:20 105 1.5 5.0 4.5 ⊚ ⊚ ⊚⊚ ⊚ ⊚ ⊚ ⊚ ora- tive paper

TABLE 3-2 Kind & thick- ness of Contact Break- Elonga- Con- Resis-protec- angle Peel ing tion Pro- Pro- Aes- Chemi- tamin- tance Metaltive with strength strength of cessa- cessa- Adhe- thetic cal ation tobase layer water at 180 of paper bility- bility- sive- appear- Safe-resis- resis- spread material Paper (μm) (°) degree* paper* (%) 1 2 nessance ty tance tance of fire EXAM- PLE 36 Al foil Decora- PU:20 105 1.55.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ tive paper 37 Cu Decora- PU:20 105 1.5 5.0 4.5 ⊚⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ sheet tive paper 38 Ti sheet Decora- PU:20 105 1.5 5.0 4.5⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ tive paper 39 Fused Paper PU:20 105 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚⊚ ⊚ ⊚ ⊚ Zn- plated steel sheet

TABLE 4-1 Kind & thick- ness of Contact Break- Elonga- Con- Resis-protec- angle Peel ing tion Pro- Pro- Aes- Chemi- tamin- tance Metaltive with strength strength of cessa- cessa- Adhe- thetic cal ation tobase layer water at 180 of paper bility- bility- sive- appear- Safe-resis- resis- spread material Paper (μm) (°) degree* paper* (%) 1 2 nessance ty tance tance of fire EXAM- PLE 40 Fused Em- PU:20 105 1.5 5.0 4.5⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- bossed plated paper steel sheet 41 Fused Crape PU:20105 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- paper plated steel sheet 42 FusedCorru- PU:20 105 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- gated plated papersteel sheet 43 Fused Calen- PU:20 105 1.5 5.0 4.5 ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn-dered plated paper steel sheet COM- PARA- TIVE EXAM- PLE 44 FusedDecora- PU:20 105 1.5 1.3 4.5 Δ X ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated papersteel sheet 45 Fused Decora- PU:20 105 2.0 I.5 4.5 Δ X ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn-tive plated paper steel sheet

TABLE 4-2 Kind & thick- ness of Contact Break- Elonga- Con- Resis-protec- angle Peel ing tion Pro- Pro- Aes- Chemi- tamin- tance metaltive with strength strength of cessa- cessa- Adhe- thetic cal ation tobase layer water at 180 of paper bility- bility- sive- appear- Safe-resis- resis- spread material Paper (μm) (°) degree* paper* (%) 1 2 nessance ty tance tance of fire COM- PARA- TIVE EXAM- PLE 46 Fused Decora-PU:20 105 3.0 2.0 4.5 X X ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated paper steel sheet47 Fused Decora- PU:20 105 0.5 0.4 4.5 X X ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive platedpaper steel sheet 48 Fused Decora- PU:20 105 0.008 5.0 4.5 ⊚ ⊚ Δ ∘ ⊚ ⊚ ⊚⊚ Zn- tive plated paper steel sheet 49 Fused Decora- PU:20 105 0.005 5.04.5 ⊚ ⊚ X ⊚ ⊚ ⊚ ⊚ ⊚ Zn- tive plated paper steel sheet

TABLE 5-1 Kind & thick- ness of Contact Break- Elonga- Con- Resis-protec- angle Peel ing tion Pro- Pro- Aes- Chemi- tamin- tance Metaltive with strength strength of cessa- cessa- Adhe- thetic cal ation tobase layer water at 180 of paper bility- bility- sive- appear- Safe-resis- resis- spread material Paper (μm) (°) degree* paper* (%) 1 2 nessance ty tance tance of fire COM- PARA- TIVE EXAM- PLE 50 Fused Dec-PU:20 105 1.5 5.0 1.8 X X ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- ora- plated tive steel papersheet 51 Fused Dec- PU:20 105 1 .5 5.0 1.5 X X ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Zn- ora-plated tive steel paper sheet 52 Fused Dec- PU:20 105 1.5 5.0 1.0 X X ⊚⊚ ⊚ ⊚ ⊚ ⊚ Zn- ora- plated tive steel paper sheet 53 Electric PVC — — — —— ⊚ ⊚ ⊚ Δ X ◯ Δ Δ Zn- plated steel sheet 54 Fused PVC — — — — — ⊚ ⊚ ⊚ ΔX ◯ Δ Δ Zn- plated steel sheet 55 Electric None — — — — — ⊚ ⊚ ⊚ X ⊚ X X⊚ Zn- plated steel sheet

TABLE 5-2 Kind & thick- ness of Contact Break- Elonga- Con- Resis-protec- angle Peel ing tion Pro- Pro- Aes- Chemi- tamin- tance metaltive with strength strength of cessa- cessa- Adhe- thetic cal ation tobase layer water at 180 of paper bility- bility- sive- appear- Safe-resis- resis- spread material Paper (μm) (°) degree* paper* (%) 1 2 nessance ty tance tance of fire COM- PARA- TIVE EXAM- PLE 56 Ply- Decora-PU:20 105 1.5 5.0 4.5 X X ⊚ ⊚ ⊚ ⊚ ⊚ X wood tive paper 57 Fused Decora-PU:4 105 1.5 4.0 1.8 X X ⊚ ⊚ ⊚ Δ Δ Zn- tive plated paper steel sheet 58Fused Decora- PU:2 105 1.5 3.0 1.5 X X ⊚ ⊚ ⊚ X X ⊚ Zn- tive plated papersteel sheet 59 Fused Decora- PU:1 105 1.5 2.0 1.2 X X ⊚ ⊚ ⊚ X X ⊚ Zn-tive plated paper steel sheet 60 Fused Decora- — 105 1.5 2.0 1.2 X X ⊚ ⊚⊚ X X ⊚ Zn- tive plated paper steel sheet

INDUSTRIAL APPLICABILITY

According to the present invention, the paper-laminated metal sheet hasa structure in which the paper is laminated on at least one side of themetal sheet, and then the protective layer is formed on the paper. Thisstructure is simple, but has advantages that the aesthetic appearance ofthe paper is imparted to the metal sheet. Thus-formed paper-laminatedmetal sheet has high strength and durability derived from the metal basematerial as well as the warm touch derived from the paper, whileeliminating a coolness and cold touch of metals. In addition, theprotective layer prevents the paper from being damaged during the timewhen the paper-laminated metal sheet is processed or is used forproducts. In addition, when the paper printed beforehand is used, higheraesthetic appearance is attained. For example, when paper printed with awoodgrain pattern is used, the paper-laminated metal sheet is valuablein various applications as a novel material with high qualityappearance.

The paper-laminated metal sheet is useful in not only applications wheremetal sheets and painted metal sheets have been conventionally used, butalso in applications where only wood materials such as plywood and resinmaterials have been used. Examples of such applications include:construction materials such as inner wall materials, floor materials,ceiling materials, interior materials, panels, and doors; furniture suchas lockers, cabinets, and counters; casing members for electricappliances; and interior materials for vehicles such as cars, train, andships. The paper-laminated metal sheet is also applicable as a materialfor vessels and metallic parts.

What is claimed is:
 1. A paper-laminated metal sheet comprising a metalbase material, a pressure sensitive adhesive agent layer or an adhesiveagent layer, a paper, and a protective layer, wherein at least a sheetof the paper is formed on at least one side of the metal base materialvia the pressure sensitive adhesive agent layer or adhesive agent layer,and the protective layer is formed on the top surface of thepaper-laminated side of the paper-laminated metal sheet, and a peelstrength at 180 degrees between the metal base material and the paperlaminated thereon is in the range between 0.01 and 5.0 kgf/10 mm inwidth, and the peel strength is smaller than a breaking strength of thepaper itself.
 2. A paper-laminated metal sheet according to claim 1,wherein the protective layer is a water-repellant film made of otherthan resins containing chlorine atoms.
 3. A paper-laminated metal sheetaccording to claim 1, wherein the protective layer is a resin filmhaving a water contact angle of 60 degree or more measured by a liquiddrop method at 23° C.
 4. A paper-laminated metal sheet according toclaim 1, wherein the paper has a maximum elongation of 2% or more.
 5. Apaper-laminated metal sheet according to claim 1, wherein the paper isdecorative paper having depressions and/or protrusions on its surface,and the depressions and/or the protrusions have a color different fromthe surrounding portions to form a visually recognizable design.
 6. Apaper-laminated metal sheet according to claim 5, wherein the decorativepaper comprises at least a paper base material, a printing ink layer,and a resin layer, and the resin layer has depressions and/orprotrusions therein.
 7. A paper-laminated metal sheet according to claim5, wherein the decorative paper has a woodgrain pattern.
 8. Apaper-laminated metal sheet according to claim 7, wherein the resinlayer of the decorative paper has depressions corresponded todark-colored portions of the woodgrain pattern.
 9. A paper-laminatedmetal sheet according to claim 7, wherein the decorative papercomprises: a first printing ink layer to be light-colored portions ofthe woodgrain pattern, the first printing ink layer being formed on theentire surface of the paper base material directly or via another layer;a second printing ink layer to be dark-colored portions of the woodgrainpattern on the first printing ink layer; and a resin layer formed on thefirst printing ink layer and the second printing ink layer, the resinlayer including a curing agent, and the second ink layer being formedusing ink including a compound which generates gas through the reactionwith the curing agent included in the resin layer, the generated gascreates bubbles at least in the resin layer positioned on the secondprinting ink layer to foam and bulge the resin layer, and then a wholeof the foamed portions are ground to form depressions in the resin layerof which bottoms correspond to the top surface of the second printingink layer.
 10. A paper-laminated metal sheet according to claim 7,wherein the decorative paper comprises: a first printing ink layer to belight-colored portions of the woodgrain pattern, the first printing inklayer being formed on the entire surface of the paper base materialdirectly or via another layer; a second printing ink layer to bedark-colored portions of the woodgrain pattern on the first printing inklayer; and a resin layer formed on the first printing ink layer and thesecond printing ink layer, the resin layer including a curing agent, andthe second ink layer being formed using ink including a compound whichgenerates gas through the application of heart, the generated gascreates bubbles at least in the resin layer positioned on the secondprinting ink layer to foam and bulge the resin layer, and then a wholeof the foamed portions are ground to form depressions in the resin layerof which bottoms corresponded to the top surface of the second printingink layer.
 11. A paper-laminated metal sheet according to claim 1, foruse in construction materials, furniture and casing members of electricappliances, and interior materials for cars, trains, and ships.